1. Field of the invention-mounted
This invention relates to a motor vehicle-mounted radio wave receiving GPS (Global Positioning System) apparatus and, more particularly, to a GPS antenna and GPS receiver to be mounted on a finished motor vehicle for positioning on the Globe by making use of a plurality of artificial satellites.
2. Description of the Prior Art
A navigation system utilizing artificial satellites is currently getting common for motor vehicles in positioning. The positioning may be performed on the ground by receiving radio waves from a plurality of GPS satellites, for example, by receiving the radio waves from three GPS satellites for two-dimensional positioning. Basing on the navigational data contained in a GPS signal received from each GPS satellite, positional information of a self-position or a receiving point such as coordinates can be reckoned in real time.
A typical motor vehicle-mounted GPS signal receiving apparatus has a fundamental structure consisting of an antenna section for receiving radio waves from artificial satellites, a preamplifier section for amplifying received satellite signals, a demodulator section for demodulating the amplified satellite signals so as to attain specific information therefrom, and a computer section for reckoning a present position from the demodulated satellite signals, whereby the preamplifier section, demodulator section and computer section are combined into one unit and installed in a main body of a GPS receiver for being placed normally at a suitable place in the motor vehicle.
On the other hand, a common antenna to be employed in the antenna section for the motor vehicle-mounted GPS receiver is a plane antenna known as a microstrip antenna. FIG. 1 is an upper perspective view showing an antenna element of a conventional microstrip antenna while FIG. 2 is a lower perspective view showing a mounting portion of the same. The microstrip antenna of the prior art shown in FIGS. 1 and 2 comprises a rectangular copper foil 2 which functions as an antenna element is mounted on an upper side of a rectangular dielectric thin plate 1, a copper foil 3 which functions as the ground for the antenna is attached to a lower side overall surface of the same dielectric thin plate 1, and a terminal 4 provided at the lower side of the microstrip antenna for deriving a received satellite signal therefrom.
According to the configuration of the prior art microstrip antenna as described above, it has been necessary for providing a motor vehicle body with a required number of through holes by drilling at the roof for penetrating the terminal 4 therethrough from the upper side to the lower side thereof, and thereby fastening the antenna on the roof with mounting bolts from the inner side of the motor vehicle at respective through holes.
In the prior art motor vehicle-mounted radio wave receiving GPS apparatus, an antenna such as the conventional microstrip antenna for receiving radio waves from the GPS satellites is a separate component of the motor vehicle, so that it has been necessary to mount on the exterior of the motor vehicle. The received satellite signals are required to introduce into the interior of the motor vehicle and that to a GPS receiver with a prescribed antenna cable, therefore, there has been such a problem as that the finished motor vehicle body should be drilled for mounting the antenna with mounting bolts and providing a through hole in order to introduce the antenna cable into the interior thereof upon installation of the radio wave receiving GPS apparatus, thus requiring troublesome extra work on the finished motor vehicle and increasing in the cost of installation. Moreover, the microstrip antenna may fall off from the motor vehicle body due to the loosening of the mounting bolts.
It is therefore an object of this invention to eliminate the problems encountered in the prior art motor vehicle-mounted GPS apparatus and to provide a microstrip antenna for a GPS apparatus which can be installed simultaneously with manufacture of a motor vehicle body and which is securely mounted.
It is another object of this invention to provide a motor vehicle-mounted GPS receiver for a GPS apparatus which can be simply installed in a finished motor vehicle.